In the fabrication of integrated circuits, one-time programmable (OTP) memories may be used to facilitate programming of certain information on-chip during fabrication processing or subsequently thereafter. So-called e-fuses have been proposed, in which a fuse link is “blown” or open-circuited to achieve programming. For example, a fuse link may be open-circuited by catastrophic electromigration or thermal rupture/melting. In such a case, a single bit may be stored because, for example, an open-circuit may be sensed and interpreted as a digital 0 and a closed-circuit may be sensed and interpreted as a digital 1. Conventional electromigration or thermal rupture based fuse based techniques, however, have several drawbacks that limit their usefulness.
For instance, conventional fuse devices require high voltages for fast programming at higher currents, and are therefore not suitable as semiconductor devices continued to be scaled down in size and voltage in advanced technology nodes, because the required high programming voltages and current may damage such on-chip semiconductor devices. In addition, existing devices are only useful for programming digital information, because an e-fuse is either blown or not, and the catastrophic failure of a fuse link cannot be controlled to allow for partial open-circuiting to facilitate the storage of continuous, non-binary information.
Therefore, a need exists for new programmable devices, such as one-time programmable devices, for analog or digital use, to overcome the limitations of electromigration or thermal rupture-based e-fuses.